J-MAN8

I'm having voltage issues on my 2018 2.7. It's got 4700 miles on it. The issue is that it runs around 12.4 on the voltage. Sometimes it's higher, but most of the time that's where stays. I'm thinking it's supposed to be in the 13.5 range. It is there after you start it, but falls to 12.4 after a minute or two and maintians. Funny thing is there is no battery light or check engine light? No codes either.

stormsearch

Welcome to the world of BMS - battery management system. First introduced by Honda awhile ago. What BMS does in order to conserve fuel, is to reduce voltage (either by command or by shutting off the alternator) so there is no torque on the engine. In order for the vehicle to be in this mode, the main two criteria is the engine to be in a low efficiency mode (high acceleration, idling) and battery state of charge is healthy enough.

J-MAN8

I was kinda wondering if that was some sort of fuel efficiency strategy. It makes sense now. I watched it while driving and it actually goes UP when I left of the accelerator. Opposite of my old school logic! Haha. Thanks again!

Takeda

An interesting article on BMS. Be careful on adding electrical accessories:

https://noln.net/2017/03/28/battery-...-smart-system/

J-MAN8

That's crazy. I watched it as I ran around this evening and it stays low as long as I'm the pedal, let off the pedal and it climbs to 14.2, falls to 13.5 and stays there till I press the pedal again. With the headlights on headed home it went to 13.4 and maintained that. It's weird how it didn't start this till now? Lol. I put 700 miles on the nGauge before it decided to do this. Oh well. At least it's not broke!

RL1990

Don't know about all of this. I have a 2009 Acura and 2 Hondas before that and none of them had a BMS. My girlfriend's Hyundai on the other hand does have a smart charging system. And I don't know about having it for fuel economy. It does do really well handling electrical loads and prolonging battery life by not charging when not needed and charging based on temperature and electrical load. It even helps with cold starts. The smart charging system turns off the alternator during startup to reduce drag on the engine.

J-MAN8

[QUOTE=RL1990;5631586]Don't know about all of this. I have a 2009 Acura and 2 Hondas before that and none of them had a BMS. My girlfriend's Hyundai on the other hand does have a smart charging system. And I don't know about having it for fuel economy. It does do really well handling electrical loads and prolonging battery life by not charging when not needed and charging based on temperature and electrical load. It even helps with cold starts. The smart charging system turns off the alternator during startup to reduce drag on the engine.[/QUOTE

I wonder if it has anything to do with the AGM batteries the for the ecoboost?

stormsearch

I was heavy into Audio systems awhile back and the voltage drop was a serious issue on the Honda's and now on the F150's. On Honda, there was a wire bypass that could be utilized. Really was only an issue for guys that were adding mega bass loads. I didn't own a Honda so not sure which vehicles were affected. This was before I became the Ford D&R for starters, batteries, alternators and the BMS system (known as the Power Supply Engineer here). I had a custom audio in my '09 F150 and was great. On my '16, I would either disable BMS (which includes S/S) or likely add a small aux battery to the system. The S/S causing more of an issue compared to lowered voltages.

stormsearch

[QUOTE=J-MAN8;5631638]The AGM battery is released due to the S/S, or what I see the wonderful Owner's Manual calls the Auto S/S. Ford has the BMS technology on most vehicles starting with the 13MY which most at the time had no S/S and standard flooded SLI batteries. And if you believe Ford added this technology for any other reason due to fuel economy, would be about 90% wrong. Smart charging is not the same as BMS, at least in Ford's terms. Smart Charging is where the PCM controls the voltage instead of the Alternator using an internal temp thermistor. The PCM in Smart Charging Systems only (not BMS), had standard voltage setpoints of >13v based on battery temperuture only. Soft start of the alternator during an engine start has been in vehicles long before Smart Charging System was put in place.

J-MAN8

I guess I've never really monitored it before on any other vehicles. I would've never know it had it not been for the nGauge turning on and off from voltage variances. Does the Super Duties do this as well?